Maxx Mazda

Hey everyone. I've noticed this certain problem mostly right after gasoline fill-ups (don't worry, once the nozzle clicks once, I stop. I don't keep shoving gas in there.) But anyways, usually right after I fill up, sitting at an intersection or whatever, the engine will drop to stall speed, then quickly pick up again. Then, it will fall back down again to the stall mark on the tach (little make just above 0) and it will repeat this process. If I tap the gas to rev the engine back up, once it goes back to idle it will continue. After driving awhile, the problem will be gone! I can't replicate it on a regular basis, it just seems to happen! I've had it on half-tanks of gas and all that before, but the best I can come up with is that it usually happens after I fill up. I've never had it actually stall, but the engine idle control keeps bumping it up from about 100 RPM, to 1500. (Yep, 100 RPM before it decides to give it more gas.)

I never noticed this problem before my engine mods (vacuum hoses, Injen CAI, Mazdaspeed exhaust) but I only had about 500 km on the car when I did the CAI and hoses, so that's not even a fill-up. I use octane 87, and just changed my oil at 5000 km, but I've had this porblem for awhile. I would take it in to work, but I can't replicate it so I don't know what to do.

Can anybody help?

Installshield

Many different problems can account for a loping idle. My P5 does not do it but my old Probe GT did. Mine would sometimes stall all together and when i would restart the engine it would surge up to 2000rpm and idle there. If you you have any leaks in your vacuum lines that could cause it. Check all your hoses. If your cylinder head has blown the gasket that could also casue idling problems although you would most likely be leaking more oil than having idle problems. clogged airfilter, leaks in the throttle body, faulty sensors could all contribute to it as well. Also your fuel pump, injectors, and pressure regulator could cause this.

I would disconnect the battery for a few minutes to reset the computer. Reconnec the battery, start the car, and let it idle for about 4 to 5 minutes and then drive it around a little bit. That should give enough time for the computer to relearn everything.

If that does not fix it maybe try getting gas somewhere else. I had a car that had a lot of trouble with certain local company's gasoline, but so did a lot of other people's cars.

If none of these work and you are sure you lines are all secured properly take it into the dealership. They can test all kinds of systems in your car that could lead them right to the problem, even if the car is not idling funny when you take it in.

Mxyzptlk

I would check the vaccum & air filter connections. Maybe the PVC?PCV valve. I don't know if you are causing it with the gas fill up. But sounds like and air fuel problem.

Maxx Mazda

I'll take it in at work tomorrow and see if my buddy will give it a look.

Out of curiousity, why was this thread moved? It's an engine question, as such was originally put inthe "Engine/Drivetrain" forum...

tattu

My engine does exactly the same thing. I even complained to my dealership and they checked the engine and told me that there are no error codes. Let me know if you find any fixes.

jstand6

I've had that problem on my car a couple of times in the past 3.5 years I've had it. I found that turning off the car and restarting seems to solve the problem. I think it's a problem with the ECU (I knew an Intel ECU would be problems!) and restarting seems to reset it and it runs normal again. Like I said, I've only experienced this a couple of times. If it's happening often, definitely take it into the dealership and have them run a diagnostic on it!

-Jerry

Unzipped

I've had the same problem on my Pro5 during the last 1-2 months. I'll be sitting at a red light and the RPM's will drop, and pop back up. It's happened 4 times so far. I've had no lights on, no fan, no AC, maybe the radio at times but that's about it. There hasnt been any pattern yet...

Took it to the dealer and they kind of laughed saying I need to duplicate it or it'll be a waste of time...

Anyone else having this problem?

My car's problem list seems to be growing uncontrolably.

This is my first NEW car and have never had so many problems...

<grumble, grumble, complain>

I wondering if I should sell myself this time... No one else seems to have any problems making the car worth selling..

PJStyles

I don't imagine it would be the sparkplug wires - the wires that actually lead to the spark plugs? I had a similar problem on a different vehicle and there ended up being a recall on this part. It caused the exact same symptoms you guys are describing here.

The car would never stall but it would flip flop back and forth when idling as if the car was going to stall.

PJStyles

nightowl

i had that problem once after a gas fill up....but i think it was due to over filling my tank......my dealer warned me about that he even said i might get a check engine light...started my car up the next morning and the problem disapeard

Maxx Mazda

Ok, I think I've fouind the cause / remedy. I was at the gas station the other day, and decided that just for the hell of it (and the insanely high gas prices for the long weekend) that I'd just fill the tank up halfway. I did, and upon starting the engine again, I had the same problem! This leads me to believe that after I add gas, the engine starts to act up. After about 10-15 mins of driving, the problem is gone!

Once home, I shut off the car, and noticed a very quiet "dripping" sound. It's barely noticeable, and you need to be in a very quiet environment in order to hear it. It almost sounds like water dripping off the top of the tank from condensation, however here's the funny thing: I opened the gas cap, and it hissed (like when you open a pop) and the dripping stopped. I started the car back up, and all was well. I'm not sure if this had anything to do with the problem, but so far I've been able to replicate the near-stalling situation 100% of the time after a fill up.

Any suggestions?

nightowl

could be wrong on this but it sounds like a pressure problem...gas tank gets to a certain pressure then it leaks out the pressure and thats when the car almost stalls....could be the type of gas too?....i'm no mechanic so i could be dead wrong about this

macdaddyslomo

too be honest,I still think the fill ups are just a coincidence..You noticed it once so thats when you are listening for it....the thing that raised an eyebrow to me is the aftermarket vacuum lines....did you get them from APC...if so,lose them..they are a big waste...they are too thin-walled and collapse under very low load or a little heat off the engine...even if they arent from APC,look for a collapsed vacuum line...time consuming,but without proper vacuum,your engine will do all kinds of crazy things...I'm pretty confident that's your problem...but I'm not APC certified or anything...althought i think the only kind of engine work i havent done is,well lets see..I have done water pumps,alternators,replaced rods and pistons,replaced cranks,timing belts,valve covers,head gaskets,cams,throttlebody,intake and exhaust manifolds,starters,fuel pumps,ac compressors,ac dryers,blower engines,wheel hubs,main bearings,trannies(auto and manual),brakes,axles,differentials,carbureautors:s p?,fuel filters,oil changes,oil seals,rotors......everything but ecu's i think...so i have a LITTLE know how and trouble shooting experience..

neuromancer

Could also be an iffy intake manifold gasket. My 90 Accord did exactly the same thing as you describe. At first it only did it once in a while...then in the end it wouldn't stop. That was actually the last straw with that car, shortly after fixing it I bought my P5.

Instead of speculating, take it into the dealer. That's why you have that warrenty you know.

Jay

Maxx Mazda

Slomo,

I've checked all of the vaccuum lines, and all are OK. (Damn process took me the last hour!) I have some really high-grade silicone hoses, not from APC though. Cost me about $80 CAD for the set. I'll see if I can find out what type, etc, but I could not for the life of me find any collapsed hoses, etc. I'll check my shop manual tonight in the troubleshooting section. I found the cause once, but I forgot so I'll have to go digging again.

I'll post my findings later.

Unzipped

It happened to me again.

This time, I hit up Silk and Spice in Marlton for some chicken and broccoli at about 12. It's about a mile from work, so lit up before I left and parked the pulled the brake when I got there. I sat, radio off, windows open staring at the rpm's. Every so often I can feel a slight "studder", the engine doesn't seem to be idling half as smooth as it once did. The needle slightly moves up and down around the 750 mark. Then it happened, twice, about 1-2 minutes apart. The rpm's dropped to 500~ mark and shot back up to 1k and leveled off. ???

So, being the paranoid freak I am, I drove home today and listened very closely to my engine. It seems I have a metallic tapping when pushing the engine a little harder than usual. Especially up hills. The tap isn't all THAT noticeable when driving.

The only other time I've heard it, and I have a witness, is pulling out of toll booths quickly. The tap is rapid, high pitched and metallic. I've heard it before and thought it might be another old car nearby...

Black Pro5 manual
All Stock
14,500 mi
Oil change every 5k

Eric